In the pharmaceutical industry, a machine is known for filling capsules, each comprising a bottom shell and a top shell closing the bottom shell.
The machine normally comprises a first wheel, on which each capsule is first positioned vertically, with the top shell on top of the bottom shell, and then opened; a conveying line connected to the first wheel to pick up the bottom shells successively and feed them along a given first path extending through at least one metering and filling device; a second wheel connected to the first wheel to pick up the top shells successively at a first transfer station; and a third wheel connected to the second wheel to receive the top shells successively at a second transfer station, and connected to the conveying line to successively receive the bottom shells, each of which is closed with the respective top shell.
The second wheel cooperates with the first and third wheel to feed each top shell along a second path of substantially the same length as the first path, and therefore in time with the relative bottom shell, comprises at least one seat for a top shell, and is mounted to rotate about a respective axis of rotation to feed the seat through the first and second transfer station.
The seat is normally connected to a suction device for removing the top shell off the first wheel and feeding it along the second path, and is connected, at the second transfer station, to a blow device to release the top shell onto the third wheel.
Given the relatively severe centrifugal forces to which the top shells of the capsules are subjected by the operating speeds of the first and second wheel, that the first and second wheel must differ fairly considerably in diameter to achieve the same length for both paths, and that the seat is normally connected to the suction device, known capsule filling machines of the above type have several drawbacks, mainly due to transfer of the top shells between the first and second wheel normally commencing upstream from the first transfer station, and so jeopardizing correct positioning of the top shells inside the seat on the second wheel and on the third wheel, and therefore closure of the relative bottom shells.
Failure to close a bottom shell results in stoppage of the machine to remove the bottom shell and relative top shell off the third wheel, and in fairly considerable downtime.